內容簡介
DNS 解析時間可能會導致使用者感知到的延遲時間增加。DNS 解析所需時間的長短是高度變異的，延遲的時間從約 1 毫秒（本地緩存的結果）到報告的常見時間為幾秒。
DNS 預取是在使用者嘗試點擊鏈接之前解析域名的一種嘗試。這是使用計算機正常的 DNS 解析機制來實現的。一旦解析了域名，如果使用者確實轉到該域，將不會因為 DNS 解析時間而造成實際延遲。當我們在頁面中遇到超鏈接時，我們會從每個超鏈接中提取域名，並將每個域名解析為 IP 地址。 所有這些工作都與用戶對頁面的閱讀同步進行，並且使用最小的 CPU 和網絡資源。當使用者單擊任何這些預解析名稱時，他們平均可以在導航中節省約 200 毫秒（假設使用者最近沒有訪問此域）。比平均節省更重要的是，用戶不會體驗到 DNS 解析的“最壞情況”延遲，這些延遲通常超過 1 秒。
外掛標籤
開發者團隊
原文外掛簡介
DNS resolution time can lead to a significant amount of user perceived latency. The time that DNS resolution takes is highly variable. Latency delays range from around 1ms (locally cached results) to commonly reported times of several seconds.
DNS prefetching is an attempt to resolve domain names before a user tries to follow a link. This is done using the computer’s normal DNS resolution mechanism. Once a domain name has been resolved, if the user does navigate to that domain, there will be no effective delay due to DNS resolution time. When we encounter hyperlinks in pages, we extract the domain name from each one and resolving each domain to an IP address. All this work is done in parallel with the user’s reading of the page, using minimal CPU and network resources. When a user clicks on any of these pre-resolved names, they will on average save about 200 milliseconds in their navigation (assuming the user hadn’t already visited the domain recently). More importantly than the average savings, users won’t tend to experience the “worst case” delays for DNS resolution, which are regularly over 1 second.
